Forensic DNA evidence in doubt?

Not without reason.

From the New York Times:

DNA Under the Scope, and a Forensic Tool Under a Cloud

Marina Stajic worked for nearly three decades as director of the forensic toxicology lab at the medical examiner’s office in New York City. Last week Dr.. Stajic, 66, filed a lawsuit against the city, claiming she had been forced into retirement last year in part because of a disagreement with her superiors over the accuracy of certain DNA tests.

There is more at stake here than Dr. Stajic’s retirement. The cutting-edge technique at the center of this legal dispute, called low copy number DNA analysis, has transformed not just police work, but also a range of scientific fields including cancer biology, in vitro fertilization, archaeology and evolutionary biology. Yet some of the technique’s applications have triggered scientific controversy.

But low copy DNA analysis can detect a mix of DNA from more than one person, and it can be hard to tell which of them is relevant to a crime.

“Maybe there’s not three people bleeding on a steering wheel, but there are three people touching it,” said Kirk E. Lohmueller, a geneticist at the University of California, Los Angeles. “Before, you didn’t have to worry about that.”

File:A small cup of coffee.JPGNow we all have to worry about it.

People can even leave DNA traces on objects they haven’t touched. More.

There is no magic truth machine. That’s the reason courts try to err on the side of innocence.

See also: The assured results of modern forensic science: Incompetent or corrupt investigators can pervert the course of justice by definition, but Balko and Koppl reveal a deeper, more serious problem: Well-meaning and competent investigators who are influenced by their bosses’ views or cultural assumptions may be far more damaging in the long run because … everyone believes them!


What if you were convicted of a crime based on falsified lab test results?: “A former Massachusetts crime lab chemist who fabricated drug test results and upended the state’s criminal justice system was sentenced to three to five years in prison on Friday, Nov. 22. Annie Dookhan pleaded guilty to 27 charges that included tampering with evidence, obstruction of justice, and perjury.”

  • Forensic investigators have a long history of displacing scientific objectivity with a belief they are “crime fighters” working with the police rather than for justice.

  • People can even leave DNA traces on objects they haven’t touched. More.
    This link is a dud for some reason. Was the page deleted?

  • Frances

    And don’t forget Charles Smith, the chief forensic pathologist for Ontario whose flawed work and faulty evidence produced a string of wrongful convictions. These have since been overturned, but the damage was done to those convicted and their families, particularly other children in the households whom the province adoped out.

  • Joy Freiheit

    “DNA DOUBT (16/09/2004)

    Police have come to rely on DNA evidence as one of their most crucial forensic tools in the fight against crime.

    But now a scientist is throwing doubt on the reliability of DNA evidence. He believes criminals can steal someone’s DNA and obliterate any trace of the real suspect. What’s more, he says crooks can easily point the DNA finger at someone else.